Psychological impact on dental students and professionals in a Lima population during COVID-19s wave: a study with predictive models

Peru was the country with the highest COVID-19 case fatality rate worldwide during second wave of infection, with dentists and pre-professional students being susceptible to infection due to clinical procedures they perform. This situation could have generated some kind of psychological disorder within this group. Therefore, the present study aimed to assess how COVID-19 pandemic affected this population group during second wave, in relation to depression, anxiety and stress. This observational and cross-sectional study in 368 Peruvian dentists (186 students and 182 professionals), was carried out during August to November 2021. The DASS-21 Scale was used to diagnose depression, anxiety and stress. For the statistical analysis, Pearson's chi-square test was used, in addition to a logit model using odds ratio (OR) to evaluate depression, anxiety and stress with the following factors: gender, age group, marital status, monthly family income, children, academic level, history of COVID-19, COVID-19 symptomatology, close relative with COVID-19, living with vulnerable people and work dedication. In addition, predictive models were constructed considering all possible significant causes. A significance level of p < 0.05 was considered. Dental students and professionals presented significant differences in levels of depression, anxiety and stress (p < 0.001, p = 0.022, p = 0.001; respectively). Male students were 56% less likely to develop stress (OR 0.44; CI 0.22–0.85) compared to females; while those unmarried were 81% less likely to develop stress (OR 0.19; CI 0.04–0.85). Likewise, those with children were 83% less likely to develop stress (OR 0.17; CI 0.06–0.52) and 65% less likely to develop depression (OR 0.35; CI 0.15–0.80). In addition, COVID-19 asymptomatics were 60% less likely to develop depression (OR 0.40; CI 0.17–0.92). However, having relatives with COVID-19 caused almost three times the probability of developing depression (OR 2.96; CI 1.29–6.79) and twice the probability of developing stress (OR 2.49; CI 1.07–5.78). As for dental professionals, it was noticed that those unmarried had almost three times the probability of developing stress (OR 2.93; CI 1.38–6.23); while those who only worked had twice the probability of developing stress (OR 2.37; CI 1.17–4.78). Dental students had a higher prevalence of depression, anxiety and stress. In addition, having children and being asymptomatic were protective predictors for depression, while being male, unmarried and having children were protective predictors for stress. However, having a relative with COVID-19 was a risk predictor for depression and stress. In professionals, only working and being unmarried were risk predictors for stress.

Population and selection of participants. The total population consisted of 532 participants, including dental students and professionals, of whom 118 and 220 were students from the Universidad Privada San Juan Bautista (UPSJB) and the Universidad Nacional Federico Villarreal (UNFV), respectively; while the professionals were 81 from the UPSJB and 113 from the UNFV. The minimum sample size was 168 participants per group, this was calculated with a formula for comparison of proportions for independent groups considering a significance level α = 0.05 and a statistical power 1 − β = 0.80, and a prevalence of students P 1 = 0.77 and professionals P 2 = 0.63. These proportions were obtained from a pilot study with 60 participants (30 students and 30 professionals).
The sample selection technique was systematic randomization for both groups and taking into consideration the eligibility criteria, 368 participants were included as the final sample (n = 368; 186 students and 182 professionals). anxiety and stress were: gender, age group, marital status, monthly family income, children, academic level, history of COVID-19, COVID-19 symptomatology, close relative with COVID-19, living with vulnerable people and occupation.
To evaluate reliability of the instrument, Cronbach's alpha was applied and a significantly acceptable value was obtained: 0.88; (95% CI 0.79-0.97). In addition, the scale was taken at two different times within 7 days to evaluate the concordance analysis of the responses, altering the order of the questions to avoid memory bias (test-retest). The concordance according to Cohen's Kappa index was very good (k = 0.87; 95% CI 0.75-0.98).
Procedure. The scales developed in Google Classroom® were distributed in a self-administered manner to each student and dental professional, sending the link to their e-mails or through the social networks with WhatsApp®, Twitter® and Facebook®. They were asked to initial their first name, last name and age (for example: CCR40), so that any repetitions could be eliminated. The survey form was also edited to allow only one mailing to the associated e-mail address. Informed consent to participate in the study was given at the beginning of the scale, followed by the indications for its development. However, everyone was free to refuse the evaluation if they did not wish to complete it during the course of the study. Only the researchers had access to the data and no personal details such as telephone number, full name and address were required. Only one submission was considered for each student and dental professional. In addition, after the entire investigation was completed, the results were sent to those who requested them to the principal investigator via email. Data analysis. Data analysis was performed with the Statistical Package for the Social Sciences (SPSS) version 24.0. Descriptive statistics were used to obtain the percentages of categorical variables. Pearson's chi-square test with Yates correction was used for bivariate analysis because it determines whether the distribution of the observed response occurs randomly or is significantly associated with a demographic variable. Mann Whitney U test was used to compare the levels of depression, anxiety and stress. Risk factors were examined by logistic regression model (logit model) using odds ratio (OR), assessing statistical assumptions such as the observations were independent, no multicollinearity, and sample size was sufficient according to the number of explanatory variables, in addition to assessing the goodness of fit in the model. All analyses were performed, considering a significance level of 5% (p < 0.05).
Bioethical considerations. All

Results
Of the 368 participating dentists, the mean age of the respondents was 25.3 ± 6.7 years and 38.4 ± 10.4 years for the 186 students and 182 professionals, respectively. The predominant gender was female (62.9%) for students and male (55.5%) for professionals. The majority of students (77.4%) were under 30 years of age, while the majority of professionals (73.1%) were 30 years of age or older. The majority of students (93.0%) and professionals (54.9%) were not married. Regarding family income, 90.9% and 61.0% of the students and professionals, respectively, earned less than US$1125 per month. Of the students, 80.6% reported having no children and 52.2% of the professionals reported having at least one child. Additionally, it could be seen that the majority of students (72.0%) study and work at the same time, while the majority of professionals (57.7%) only work, 47.8% of them holding a Master's degree (Table 1). On the other hand, the majority of students (59.7%) and dentists (71.4%) reported that they had not been ill with COVID-19 since the pandemic began. In that sense, the majority of students (56.5%) and professionals (69.2%) did not report having felt any symptoms of COVID-19 during the pandemic. However, 79.6% of students and 69.8% of professionals report having had at least one close relative with COVID-19. Finally, the majority of students (65.6%) and professionals (61.0%) reported living with people vulnerable to COVID-19. (Table 1).
Of the 186 dental students, 41.4%, 44.1% and 47.3% presented stress, anxiety and depression respectively, with the moderate level being the most prevalent in all of them (Fig. 1). On the other hand, of the 182 dental professionals, 24.7%, 33.0% and 28.6% presented stress, anxiety and depression respectively, with the mild and moderate levels (Fig. 2) being the most prevalent. Therefore, when comparing the levels of depression, anxiety and stress among students and dental professionals, significant differences were observed (p < 0.001, p = 0.022, p = 0.001, respectively) ( Table 2).
Regarding dental students, it could be observed in the crude model of logistic regression analysis that no factor was significantly influential for anxiety (p > 0.05). However, the variables children (p = 0.004), symptoms of COVID-19 (p = 0.025) and close relative with COVID-19 (p = 0.029) were identified as significantly influential factors for depression. The variables gender (p = 0.031), marital status (p = 0.041), children (p = 0.002) and close relative with COVID-19 (p = 0.034) were also identified as significantly influential factors for stress. Therefore, we considered adjusting the model for depression and stress variables, finding that men were 56% less likely to develop stress than women (OR 0.44; CI 0.22-0.85) (p = 0.015), while those who were not married had 81% less likely to develop stress than those who were married (OR 0.19; CI 0.04-0.85) (p = 0.029). In addition, those    Table 5).
Regarding dental professionals, it could be observed in the crude model of logistic regression analysis that no factor was significantly influential for depression (p > 0.05) and anxiety (p > 0.05). However, marital status (p = 0.019) and occupation (p = 0.023) were identified as significantly influential factors for stress. Therefore, we considered adjusting the model for the stress variable taking into account the variables marital status and occupation, finding that the unmarried were almost three times more likely to develop stress than married ones (OR 2.93; CI 1.38-6.23) (p = 0.005). In addition, those who only worked were twice more likely to develop stress than those who worked and studied (OR 2.37; CI 1.17-4.78) (p = 0.016). (Table 6).

Discussion
The Occupational Safety and Health Administration (OSHA) has placed dental professionals and students in the "very high risk of exposure" category because they are exposed to known or suspected sources of SARS-Cov-2 virus during specific procedures that generate contaminated bioaerosols [17][18][19] . For this reason, the performance of clinical procedures produces significant physical and psychological stress on dental students and/or dental care professionals, leading to burnout, depression, stress and anxiety 12 . As a result, this psychological impact could weaken their immunity and make them more prone to health problems 11,[34][35][36] , and could have repercussions on their academic and professional performance 12 . For the above reasons, the present study aimed to assess how the COVID-19 pandemic affected dental professionals and students in relation to the level of anxiety, stress and depression.
When comparing the levels of depression, anxiety and stress between dental students and dental professionals, the students presented significantly higher levels of these disorders, perhaps because during the pandemic, the students had a lack of interpersonal communication due to social distancing 11 . In addition, they had to deal with online learning, having to adapt to technology and face problems such as not having a stable Internet connection 11 . Likewise, if we consider that virtual education has certain limitations in clinical training, which mainly requires manual practice 37 , uncertainty may have been generated in them regarding the development of their skills with patients 13 . This is in agreement with what was reported by Ali et al. who concluded that the students were the ones who experienced the greatest stress 11 . Likewise, our findings agree with Odriozola et al. who reported significantly higher levels of stress, anxiety and depression in students compared to the different groups of university employees 13 . Furthermore, it was observed in the present study that 41.4%, 44.1% and 47.3% of dental students presented stress, anxiety and depression, respectively; these results were slightly higher than those obtained by Hakami et al. who found a prevalence of stress and anxiety of 34.9% and 37.0%, respectively 12 . Similarly, the results obtained in the present study were slightly higher than those reported by Santabarbara et al. www.nature.com/scientificreports/ who in two meta-analyses of research conducted on dental students in relation to the prevalence of anxiety and depression, found prevalence of 35% and 37%, respectively 24,25 . On the other hand, in the present study dental students reported 44.1% and 47.3% for anxiety and depression respectively. When comparing these values with results obtained in the meta-analysis carried out by Batra et al. in health professionals, it was found that anxiety in nurses was 39.3% and in physicians 32.5%, obtaining 42.4% and 39.1% for depression in the same professionals, respectively 38 . The higher percentages we obtained could be explained by the fact that university students are more susceptible to psychological disorders due to several challenges they are exposed to 8 , which are further increased by the clinical procedures inherent to dental profession. In the present study, regarding dental students, it was observed that according to gender, males were less likely to develop stress than females, which is similar to the findings of Hakami et al. 12 and Ali et al. 11 who found that female students were more depressed, anxious and stressed than males. This could be explained by the studies of Farooq et al. 39 and Holtzman et al. 40 , who reported that females were more sensitive to particular situations under pressure. Another reason according to Hernández et al. 41 could be neuroticism (trait of being anxious and emotionally vulnerable) which is more common in women. However, these findings differ from those reported by Cao et al. 14 and Cayo et al. 10 who reported no significant difference according to gender, probably due to the fact that both studies were conducted before mid-2020, when the infodemic was widely disseminated in social networks and broadcast media 42 , which could have generated a similar psychological impact on both genders when faced with a totally new situation. Regarding marital status, it was found that the unmarried were less likely to develop stress than the married, which could be due to the fact that students who have partners or spouses have the complicated role of maintaining their relationship and sharing time between their families and their academic studies 12 . Those who had children were less likely to develop stress and depression than those who did not have children. These findings are justified since students living alone experience higher levels of depression, anxiety and stress compared to those who live with 2 or more people 12 . In addition, having their children at home under constant supervision may have influenced them to have a certain degree of peace of mind. On the other hand, those who became ill with COVID-19 asymptomatically were less likely to develop depression than those Table 5. Multivariate logistic regression model of Depression, Anxiety and Stress in dental students according to their associated factors. *p < 0.05significant association according to regression model (a: was not significant in the adjusted model). a: Gender was not included in the adjusted model for anxiety as a p > 0.05 was obtained. The model effect size (Nagelkerke's R2) for depression was 0.210 and for stress was 0.214. www.nature.com/scientificreports/ who did not report becoming ill with COVID-19. This could be due to the fact that the first group had previous experience and acquired immunity to the disease, giving them a sense of security and confidence, in contrast to those who had not yet become ill. Finally, those who had close relatives with COVID-19 were almost three times more likely to develop depression and twice as likely to develop stress than those who did not have a close relative with COVID-19. This is consistent with that reported by Cao et al. 14 who found that college students' anxiety about the pandemic was significantly associated with the presence of a family member or acquaintance infected with COVID-19.
With regard to the dental professionals in this study, 24.7%, 33.0% and 28.6% presented stress, anxiety and depression, respectively; these findings are discordant with those indicated in the study by Nayak et al. in which they refer values of 17.97%, 56.2% and 42.28%, respectively. This is probably due to the fact that this study was carried out between May and June 2020 43 , a time of greater uncertainty since vaccines were not yet available  www.nature.com/scientificreports/ and social interaction was restricted, which could have generated higher levels of anxiety and depression 23 . For 2021, the lower prevalence percentages we found could be due to the positive adaptation of professionals to a context of adversity (resilience) as reported by Barzilay et al. 44 , Parvar et al. 45 and Cayo et al. 46 . In reference to the factors "children" and "close relative with COVID-19", our findings agree with those obtained by Li et al. 47 who reported that among the risk factors for developing stress, anxiety and depression is the number of children, with those who had two or more children being more susceptible. In addition, they also reported that having family members or relatives with suspected or confirmed COVID-19 was one of the risk factors for depression and stress. Regarding age, our findings agree with Owen et al. 21 who indicated lower levels of stress in the 18-24 age group compared to other age groups. However, they differ with Nayak et al. 43 who reported that those aged 30 years and younger had higher levels compared to the other age groups. This is probably because Nayak et al. 43 conducted their study between May and June 2020 unlike Owen et al. 21 and the present study which were conducted in 2021. The timing of the survey may have influenced the lack of resilience of younger people in this complex circumstance 48 and the lack of socialization 49,50 generating a greater psychological impact. On the other hand, the older the age, the greater the responsibilities and the greater the job and economic prospects, which could lead to increased worries and uncertainty. With regard to marital status, unmarried dental professionals were almost three times more likely to develop stress than married ones, which coincides with Nayak et al. 43 who found a significant association between stress and marital status, where single people had higher scores than married ones. This may be explained by the fact that loneliness is a risk factor for developing mental disorders under situations of constant pressure 51 , and added to this, the social isolation resulting from the pandemic 2,49,50 , may have induced them to demand greater adaptation than usual (stress). In reference to occupation, it was found that those who only worked were twice as likely to develop stress as those who worked and studied. This result can be explained by the fact that they were exposed to greater psychological distress due to the type of care provided by dentists 19 , dealing with different people who have different demands and expectations 52 , educed income due to the lower number of visits 5 , and reduced work time due to the fear of becoming infected. On the other hand, those who worked and studied shared their time in both activities, reducing the period of clinical work and therefore had less risk of exposure to the virus, which could have given them a greater sense of peace of mind. It has been reported that prolonged and untreated psychological disorders would result in high levels of burnout in the future 11,21,34,35 . This study is important because some sociodemographic factors have been found to predict the development of depression in dental students and stress in dental students and professionals using two predictive models in students and one predictive model in Peruvian dental professionals, after they faced the highest COVID-19 fatality rate worldwide during the second wave of infection 16 . Furthermore, in the present study, unlike other studies, it was observed that the type of dedication of the professionals was an influential factor significantly related to the development of stress. Likewise, having been asymptomatic when they became ill with COVID-19 was a protective factor for depression in the students. These results may be useful for competent authorities to promote strategies to provide adequate psychological support, which is vital for students and health professionals, since providing mental health support is as important as physical protection during the pandemic.
The present study had some limitations, such as not being able to evaluate the respondents in person, since at the time the survey was conducted, the country was in a national emergency and social isolation was mandatory. Likewise, students from all academic years were not taken into account because first year students take basic science subjects that could be taken virtually. In addition, since they are not required to attend patients and perform dental procedures, they might not be exposed to higher levels of depression, stress and anxiety since they do not need to develop manual care skills 37 and are not at risk of exposure to biocontaminated aerosols. On the other hand, it should be recognized that due to the sample size used in this study, the predictive models generated should be taken with caution, since it is necessary to assess in future studies with population-based design other possible predictor variables according to social, political and economic realities in which dental students and professionals develop.
It is recommended that the levels of depression, anxiety and stress in dental professionals and students in different geographical areas be compared to improve knowledge in this regard, since Cao et al. 14 suggest that living in urban areas is conducive to reducing anxiety. On the other hand, longitudinal studies are needed to evaluate the psychological impact of COVID-19 and the level of acceptance of the therapeutic support received. In this regard, it is suggested that the authorities of professional schools and universities take into account the organization of timely plans and strategies for mental health care and physical protection in the pandemic context 20 .

Conclusions
In summary, with the limitations of this cross-sectional study, it can be concluded that dental students from two universities in the Peruvian capital had a higher prevalence of depression, anxiety and stress during the second wave of COVID-19; in addition, having children and being asymptomatic were protective predictors for depression, while being male, unmarried and with children were protective predictors for stress. However, having had a close relative with COVID-19 was a risk predictor for depression and stress. In dental professionals, only working and being unmarried were risk predictors for stress. The higher frequency of psychological disorders obtained for students indicates the greater impact that COVID-19 pandemic had on them. It is important that psychological support and intervention programs that promote resilience are managed in a timely manner for this population in order to facilitate post-traumatic growth. On the other hand, none of the factors considered in this study was a predictor for anxiety in both dental students and dental professionals.

Data availability
All data analyzed during this study are available from the corresponding author on reasonable request.